In <I>Drosophila </I>the three <I>yolk protein (yp) </I>genes are expressed in the adult female fat body and ovary. The yolk proteins (YPs) are stored in the oocyte for utilisation during embryogenesis. Within the intergenic region of <I>yp2 </I>and <I>yp2</I>, a fat body enhancer (FBE) and two ovarian enhancers have been found to direct YP1 and YP2 tissue- and sex-specific expression. The male and female forms of Doublesex protein (DSX<SUP>M</SUP> and DSX<SUP>F</SUP> respectively) have been found to bind to the FBE and are thought to confer the sex-specificity of <I>yp</I> expression to the fat body of females only. The <I>dsx</I> gene is at the end of the sex determination pathway, other genes that operate from this branch of the pathway include <I>hermaphrodite (her) </I>and <I>intersex (ix)</I>, and it is possible that HER and IX proteins could also regulate <I>yp </I>gene expression. Upstream of <I>yp3</I> are sequences that direct female-, fat body-specific <I>yp3</I> expression (FBE3) and ovarian-specific <I>yp3</I> expression (OE3). This project involved analysis of FBE3 and OE3 to gain further understanding of the regulation of <I>yp3</I> expression. The role of DSX in the regulation of <I>yp3</I> has been investigated; the FBE3 was divided into smaller subfragments and it was determined that one of these fragments can bind DSX <I>in vitro. </I>These subfragments were cloned into reporter gene constructs to test their capabilities in directing correct <I>lacZ</I> expression pattern <I>in vivo</I>, using P-element mediated transformation. This revealed that the fragment capable of binding DSX <I>in vitro,</I> could direct <I>lacZ</I> expression in fat body cells, but this expression was not sex-specific, both male and female fat bodies showed reporter gene expression. C/EBP was reported to bind to the FBE <I>in vitro</I> and considered to be a potential activator of <I>yp</I> gene expression. From C/EBP mutant analysis, there was no observed difference from wild type in the level of YP expression <I>in vivo</I>; thus it is unlikely that C/EBP has a regulatory role in <I>yp</I> gene expression in the fat body.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:652772 |
| Date | January 1998 |
| Creators | Hutson, Simone Frances |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15082 |
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